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The Andromeda (M31) galaxy subtends nearly 100 sq. deg. on the sky, withsevere contamination from the Milky Way halo stars whose surface densitydisplays a steep gradient across the entire M31 field-of-view. PlanetaryNebulae (PNe) are a population of stars firmly associated with M31, that areexcellent tracers of light, chemistry and motion in galaxies. We present a 16sq. deg. survey of the disk and inner halo of M31 with MegaCam@CFHT to identifyPNe, characterize their luminosity-specific PN number and luminosity function(PNLF). PNe were identified based on their bright OIII 5007 $\unicode{x212B}$emission and absence of a continuum. Subsamples of the faint PNe wereindependently confirmed by matching with resolved Hubble Space Telescopesources from the PHAT survey and spectroscopic follow-up observations withHectoSpec@MMT. The current survey reaches 2 mag fainter than the previousmost-sensitive survey. We identify 4289 PNe, of which only 1099 were previouslyknown. By comparing the PN number density with the surface brightness profileof M31 out to ~30 kpc along the minor-axis, we find that the stellar populationin the inner halo has a 7 times larger luminosity-specific PN number value thanthat of the disk. It indicates that the stellar population at deprojectedminor-axis radii larger than ~10 kpc is different from that in the M31 disk. Wemeasure the PNLF and find a bright cut-off and a slope consistent with theprevious determination by Ciardullo et al. (1989). Interestingly, it shows asignificant rise at the faint end, present in all radial bins covered by thesurvey, much steeper than that observed for the Magellanic clouds and Milky Waybulge. M31 shows two major episodes of star formation and the rise in the faintend of the PNLF is possibly associated with the older stellar population. Itmay also be a result of varying opacity of the PNe.

The survey of Planetary Nebulae in Andromeda (M31): I. Imaging the disk and halo with MegaCam@CFHT